The present invention relates to a compressor that is driven by a drive motor provided with a cooling jacket thereby reducing vibration and noise upon the compressor being run.
Various compressors are widely applied to air conditioners for domestic and vehicle use. In recent years, a compressor for use in a fuel cell system has been flourishingly developed so as to supply an electrode of a (hydrogen-oxygen type) fuel cell with compressed gas (one of hydrogen, oxygen and air) in order to reduce environmental problems. As a typical example of such a compressor, a scroll type compressor, which is compact and highly efficient, are proposed. The scroll type compressor is normally constituted of a fixed scroll member, a movable scroll member and a drive motor. The fixed scroll member is fixed to a housing. The movable scroll member is arranged so as to face the fixed scroll member. The drive motor drives the movable scroll member. A compression region is defined between the fixed scroll member and the movable scroll member. Gas in the compression region is moved from an inlet formed on the outer periphery of the fixed scroll member toward an outlet formed at the center of the fixed scroll member by orbiting the movable scroll member around an axis of the fixed scroll member while reducing its volume. Thus, the gas is introduced into the compression region, compressed therein and discharged therefrom repeatedly.
Any types of compressors are required to be not only compact and lightweight but also relatively highly efficient for producing relatively enough discharge capacity. Therefore, the drive motor is required to drive the compressor even under the conditions of relatively high load and relatively high rotational speed. When the drive motor is used under such a condition, a relatively large amount of heat such as Joule heat and iron loss is generated. The heat causes the damage of the drive motor, thereby reducing the lifetime of the drive motor. For this reason, the effective radiation of the heat is required. If the inside of the drive motor is opened to the outside thereof, the inside of the drive motor can be cooled down by the air. However, under the substantially airtight condition of the inside of the drive motor, the drive motor is required to be frequently cooled down by water. Therefore, a water jacket is normally arranged on the side of the outer circumference of a motor housing so as to surround the drive motor, thereby cooling the drive motor with water.
Japanese Unexamined Utility Model Publication No. 5-41380 discloses this type of water jacket. In the constitution, a recess as a cooling channel of a water jacket is formed on the side of the outer circumference of a motor housing. The recess is tightly covered with a flexible thin plate. Thereby, the water jacket is formed integrally with the motor housing.
However, such a winding water jacket tends to increase the number of parts and a space for installing the parts or a process for installing the parts. In place of the winding water jacket, a new cooling jacket will be proposed. That is, a refrigerant passage as a cooling channel is formed by closing the recess formed on the outer circumference of the motor housing with an outer cylinder.
In this case, since the outer cylinder is used for closing the recess, a fastener and a seal for connecting one end of the plate in the circumferential direction of the winding water jacket to the other end thereof can be omitted. Therefore, a space for installing the fastener can also be omitted. In addition, the outer cylinder is easily mounted on the motor housing since the outer cylinder is simply fitted around the motor housing. Thus, the cooling jacket such as the water jacket that has a relatively small number of parts and that is compact and easy to mount is obtained. In the present embodiment, the recess formed on the outer circumference of the motor housing constitutes a refrigerant passage.
Even though the water jacket has such a structure, a seal such as an O-ring is required to interpose between the motor housing and the outer cylinder. Such a seal may sufficiently prevent water from leaking.
However, only the seal cannot sufficiently restrict rotation and movement in the axial direction of the outer cylinder. For this reason, the motor housing is required to restrict the outer cylinder by fastening at least one fixture such as a bolt or by press-fitting the motor housing into the outer cylinder. In a sense, the outer cylinder is sufficiently fixed to the motor housing even by one bolt only if the motor housing restricts the outer cylinder.
In a state that a compressor having the outer cylinder fixed by one bolt is run, when vibration and noise are measured and analyzed, however, it is confirmed that the vibration and noise increase more than those of a state that a compressor having the outer cylinder fixed by a plurality of bolts is run. Such vibration and noise make drivers uncomfortable. Therefore, reinforcement is required. In a case that an oscillating source and a sound source do not exist around the circumstances, especially when a compressor for use in a fuel cell system in an electric car is employed, the vibration and noise of the compressor are noticeable.
The present invention addresses a compressor that can reduce vibration and noise when a cooling jacket for cooling a drive motor is constituted of a motor housing and an outer cylinder.
According to the present invention, a compressor has a compression unit, a drive motor, a motor housing and an outer cylinder. The compression unit compresses fluid. The drive motor drives the compression unit. The motor housing surrounds the drive motor. The outer cylinder is mounted on an outer circumferential side of the motor housing for defining a cooling jacket between the outer cylinder and the motor housing for cooling the drive motor by a refrigerant flowing in the cooling jacket. The outer cylinder is directly or indirectly fixed to the motor housing by fastening a plurality of bolts or by press-fitting.
Furthermore, according to the present invention, the following features are obtained. A scroll type compressor has a motor housing, a drive motor, a center housing, a fixed scroll member, a movable scroll member and an outer cylinder. The drive motor is surrounded by the motor housing. The center housing is fixed to the motor housing. The fixed scroll member is fixed to the center housing. The movable scroll member is placed between the center housing and the fixed scroll member while engaging with the fixed scroll member. The movable scroll member is driven by the drive motor for compressing fluid between the fixed scroll member and the movable scroll member. An outer cylinder is mounted on an outer circumferential side of the motor housing for defining a cooling jacket between the outer cylinder and the motor housing for cooling the drive motor by a refrigerant flowing in the cooling jacket. The outer cylinder is fixed to the center housing by fastening a plurality of bolts or by press-fitting.